Lubricant



Patented Jan. 4, 1944 John C. Zimmer, Union, N. 1., assignor to Standard Oil Development Company, a corporation of Delaware N Drawing. Application December 2, 1941 Serial No. 421,283

-3 Claims. (Cl. 252-35) This invention relates tolubricants, and more particularly tocompounded lubricants comprising mineral oil and lead soap.

There'are many lubrication problems, such as the lubrication of high-speed gears, roller bearings, gear trains, etc., for which plain mineral oil does not have a sufliciently strong lubricating film, and for such purposes lead soaps have been incorporated into the mineral oil in order to increase the-lubricating film strength thereof. One difliculty with the use of such blends, however, is that under some circumstances; such lubricants have a great tendency to foam, especially in the presence of slight amounts of moisture,

as in the lubrication of machinery or other industrial equipment where water occasionally becomes splashed onto the moving metal parts being lubricated.

The primary object of the present invention is to prevent the foaming of suchlead-soap com-- pounded lubricants. u

It has now been found (and this is the primary feature of the present invention) that the foam ing of such lead-soap compounded lubricant can ;be prevented by incorporating a small amount of an aluminum soap into compounded lubricants containing mineral oil and lead soap.

of paraflin wax, or liquid fractions of substantially saturated petroleum hydrocarbons. Also mixtures of these different types of soaps may be used.

The lubricating oil base stock to be used may" be any mineral .011 base stock commonly used for such purposes and may be derived from various types of crudes, such as paraflinic, naphthenic or mixed base crudes. The viscosity range should preferably be from 50 to about 600 secends Saybolt' Universal at 210 F. It is also generally preferable to use a low cold test oil, i.'e., one having a pour point below 10 F. I y

The lead soaps to be compounded with the mineral oil base stock may be any oil-soluble lead soap having the property of greatly increas-' ing the lubricatingfllm strength. Ordinarily .it is preferred to use lead soaps of carboxylic acids, such as higher fatty acids, e. g., oleic acid, stearic acid, etc., or of naphthenic acids, preferably those The amount 'of such aluminum soaps required to prevent foaming of the lead-soap compounded lubricant will, of course, vary to some extent according to the viscosity and other characteristics of the base stock as well as upon the amount of lead soap blended therein, and upon the severity of the foam-producing tendencies resulting from the particular operating conditions under which the lubricant will be used, such as .the speed of rotationof gears, the relative tendency to whip air into the lubricant and the relative amount of contact with moisture. Gen erally, however, .05-3% of the aluminum soap shouldbe used, andpreferably about (LS-2%.

Although it is believed that the invention applies particularly to aluminum soaps as described above, it is believedthat the invention applies more broadly to soaps having a trivalent positive ion, so that specifically, iron soaps such as ferric stearate, ferric naphthenate, etc., could be used instead of aluminum soaps, and in the similarly small amounts specified. The advantages of theinvention willbe readily observed from a consideration "of the following table of foaming test data. In these tests, compounded lubricants were prepared by blending 10% by weight of lead soa'p into a lubricating oil base stockderived from an asphaltic type' crude having light, medium, and heavy viscOsities. In

each case the compounded lubricant was subjected to the foaming test (a tentative standard o R. P.'M. for fifteen minutes, and measuring the derived from a gas oil out of petroleum, although,

mineral oil of the same viscosity.

The aluminum soap to be incorporated into the I above-described compounded lubricants is preferably aluminum stearate, although, if desired, one may use other aluminum soaps, such as the palmitate, oleate, naphthenateychelate, capryl or hexyl oxy acetate, phthalate, or the aluminum soap of the fatty acids produced by the oxidation increase in volume, which is, of course, due to the foaming. Then similar tests were made on. the same lubricants to. which was added a small amount of aluminum stearate, ranging from 1% It is noted in the above table that in all three tests A, B, and C, the use of a small amount of anism 01 the operation of the present invention is not-knownwith certainty, it is believed that the successful results are possibly due to a lowering of the surfacetension effected by the aluminum soap.

Other tests using similarly small amounts of aluminum naphthenate indicate that this material is also very eil'ective as a defoaming agent for lead-soap lubricants.

In addition to the above-described primary ingredients of the composition of this invention,

other addition agents which are known to the art may also be incorporated, as for instance, high molecular weight hydrocarbon polymers, e. g., polybutene having a molecular weight above 1,000, especially such polymers having a molecular weight above 30,000, pour depressors, such as those made by Friedel-Crafts condensation of chlorinated paraiiin wax with naphthalene, of which the material marketed under the tradename Parafiow is representative, sulfurlzed fatty oils and other products, obtained by suliurization, sulfur-chloride treatment and halogenation of mineral and fatty oils. Other soaps, such as those of sodium, calcium, etc., may be included to obtain special products, and small amounts of glycerine, alcohols, esters, or amines may be added as modifying agents for the aluminum soaps. It is not intended that this invention be limited to the particular materials which have been 6 given merely for purposes of illustration, nor unnecessarily by. any theory as to the operation of the invention, but only by the appended claims in which it is intended to claim all novelty inherent in the invention as well as the equivalents 10 coming within the scope and spirit of the invention.

I'claimz, 1. A lubricant comprising a major proportion of a mineral lubricating oil having a viscosity of about 50-800 seconds Saybolt at 210 F., about 5-2.0% by weight of an oil-soluble lead soap, and about .05-3% of an oil-soluble aluminum soap. 2. A lubricant comprising a major proportion of a mineral lubricating oil base stock having a viscosity of about 50-600 secondsSaybolt at 210 F. and a pour. point below 10 F., about 5-20% by weight of an oil-soluble lead soap of a carboxylic acid selected from the group consistin of higher fatty acids and naphthenic acids, and about .05-3% of an oil-soluble aluminum soap of a carboxylic acid selected from the group consisting of higher fatty acids and .naphthenic acids. l 3. A lubricant comprising a major proportion of a mineral lubricating oil base stock having a viscosity of about -600 seconds Saybolt at 210 F. and a pour point below 10 F., about 5-20% by weight of lead oleate, and about 0.5-2% by weight of aluminum stearate. d

, JOHN c. ZIMMER. 

